Thiophosphates of polyoxyethylene compounds



United States Patent Ofl ice 32%,43 Patented Get. 26, 1965 3,214,423 THIUPHOSPHATES F PQLYQXYETHYLENE COMPOUNDS John D. Zach and Francis A. Hughes, Wilmington, Del.,

assignors to Atlas Chemical Industries, Inc., Wilmington, Del., a corporation of Delaware No Drawing. Filed Apr. 21, 1961, Ser. No. 104,537 3 Claims. (Cl. 260-975) This invention relates to thiophosphates of polyoxyethylene compounds. In particular, it relates to watersoluble and water-dispersible thiophosphates of polyoxyethylene compounds which are useful as lubricants in aqueous metal cutting, coolant solutions.

In metal machining operations, tremendous forces are involved in the shearing or tearing action which causes metal chips to peel off of the workpiece during the machining. As a result of the tremendous forces which are exerted, a great amount of heat is generated during the metal cutting which must be dissipated either in a stream of cooling fluid coolant or by conduction into the tool and the metal workpiece.

The two principal types of coolants used in metal machining operations are light petroleum oils and water containing corrosion inhibitors and lubricants. In the cutting process, the coolant has two primary functions: (1) the reduction of friction between the metal chip and the tool face which affects cutting speed, tool life, surface finish and power consumption and (2) the removal of heat which also increases the tool life and permits faster cutting.

The type of coolant used depends on the material being machined and the cutting speed. When high speeds are used, cooling is the primary requirement, and water is more effective than oil because of its higher specific heat. The heat transfer rate of aqueous coolants is improved by the use of surface-active materials which lower the surface tension of the water and improve the ability of the water to Wet the metal surfaces. Corrosion inhibitors are generally incorporated in aqueous coolants to prevent corroding and pitting of the machined workpiece and of the cutting tool.

The metal machining industry desires more effective and cheaper chemical additives for aqueous coolants, which additives will help to speed up production while saving on power consumption and on tool costs through longer tool life.

It is an object of this invention to provide water-soluble thiophosphates of polyoxyethylene derivatives of fatty alcohols, fatty amines, fatty amides, fatty acids, hydroxy esters of fatty acids and alkyl phenols having from about 8 to about 18 carbon atoms in the alkyl chain.

Another object of the invention is to provide an improvement in aqueous coolant compositions used in metal cutting operations.

A further object of the invention is to provide a phosphorus sulfide derivative of a polyoxyethylene compound which is useful as a lubricant in aqueous coolants for metal cutting.

Other objects and purposes of this invention will be apparent to those skilled in the art from the description which follows.

It has been discovered that polyoxyethylene derivatives of fatty alcohols, fatty amines, fatty amides, fatty acids, hydroxy esters of fatty acids and alkyl phenols having from about 8 to about 18 carbon atoms in the alkyl chain can be reacted with phosphorus sulfides to form thiophosphate products which are water-soluble or Waterdispersible and which are useful as lubricants in aqueous coolants for metal cutting. In accordance with this invention, the thiophosphate products may be prepared by slowly adding a phosphorus sulfide to a polyoxyethylene derivative at about room temperature. After all of the phosphorus sulfide is added, with an exothermic release of heat during the addition, heat is applied to the reactants and the reaction temperature is raised to the range of about 60 C. to about 150 C., with temperatures of about C. being preferred. The reactants may be held at an elevated temperature for several hours to complete the reaction during which hydrogen sulfide is liberated. Then the reaction mixture may be purged with nitrogen for about 30 minutes in order to remove trapped hydrogen sulfide. The reaction mixture is allowed to cool to room temperature, and the resulting product is a thiophosphate compound which may be either water-soluble or waterdispersible.

When phosphorus sulfide is reacted with the polyoxyethylene derivatives, varying amounts of sulfur are lost, principally as H 8, depending upon the nature of the reactants, their reacting proportions and reaction conditions. Thus the resulting products vary considerably in composition with respect to the phosphorus to sulfur ratio. The thiophosphate products of this invention include mixtures of thiophosphates esters of such types as wherein R is a radical of a polyoxyethylene derivative and R is hydrogen or a cation.

In carrying out the reaction, the reactant proportions and the reaction temperatures are not very critical. Generally, one may react from about 1.8 to about 3.0 equivalents of hydroxyl in the polyoxyethylene derivative per phosphorus atom in the phosphorus sulfide compound, with about 2 equivalents of hydroxyl being preferred. As previously stated, the preferred reaction temperature is about 120 C. though other reaction temperatures, such as about 60 C. to about C. may be used.

The reaction may be carried out in either the presence or absence of inert diluents or solvents. If such inert diluents or solvents are used, they may be removed later by vacuum stripping. Water-soluble diluents or solvents may be left in the product provided that they do not adversely affect the properties of the product.

Any of the various phospho-sulfurization agents may be used to prepare the thiophosphate compounds of this invention, such as for example phosphorus pentasulfide, phosphorus sesqui-sulfide, etc.

Many different types of polyoxyethylene compounds may be used to prepare the thiophosphate compounds in accordance with this invention. Polyoxyethylene derivatives of fatty alcohols, fatty amines, fatty amides, fatty acids, hydroxy esters of fatty acids and alkyl phenols having from about 8 to about 18 carbons atoms in the alkyl chain are operative, provided however, that the polyoxyethylene derivative should be selected from those compounds which yield a water-soluble or water-dispersible thiophosphate compound. As used in this specification, the term Water-soluble thiophosphate compound is meant to include compounds which may be considered insoluble in water but are Water dispersible. The water solubility or dispersibility requirement is essential in order that the thiophosphate compound can be formulated with water and corrosion inhibitors to produce improved aqueous coolants for metal cutting. With respect to water solubility or dispersibility, it has been found that the functionality, that is reactive sites, of the polyoxyethylene compound should preferably be no more than two. Polyoxyethylene compounds having higher functionality yield polymeric products when reacted with phosphoro-sulfurization agents, which polymeric products are generally water-insoluble and very difficult to handle. If the thiophosphate has poor solubility or dispersibility in water, this may be overcome by incorporating an emulsifier in the aqueous coolant solution to help disperse the thiophosphate compound.

In general, it is preferred that the polyoxyethylene fatty compound contain a long chain lipophilic radical, having from about 12 to 24 carbon atoms, for fatty alcohols, fatty amines, fatty amides, fatty acids and hydroxy esters of fatty acids which contain long chain lipophilic radicals may be derived from naturally occurring fats, and therefore are relatively inexpensive. In addition the long chain lipophilic radical contributes to the lubricating effect of the thiophosphate compound when it is used in aqueous coolant solutions. The ethylene oxide chain length of the polyoxyethylene compound may vary so long as the resultant thiophosphate compound is watersoluble or water-dispersible. Generally, greater amounts of ethylene oxide present in the polyoxyethylene compound tend to render it more water-soluble. If the polyoxyethylene compound contains a long chain lipophilic radical, the ethylene oxide content necessary to yield a water-soluble polyoxyethylene compound will vary with the type and size of the lipophilic radical present, and usually, larger lipophilic radicals require more ethylene oxide to render the resultant compound water-soluble. For the purposes of this invention, it is generally preferred that the ethylene oxide content of the polyoxyethylene compound range from about 8 to about 35 moles per mole of polyoxyethylene compound.

Examples of polyoxyethylene compounds which may be used to prepare thiophosphate compounds in accordance with this invention may be found in the following United States patents: 1,970,578, to Conrad Schoeller and Max Wittwer; 2,002,613, to Ludwig Orthner and Helmut Keppler; 2,085,706, to Conrad Schoeller and Max Wittwer; and 2,174,760, to Hermann Schuette and Max Wittwer.

The thiophosphates of polyoxyethylene compounds are effective in improving the lubricity of aqueous coolants used in metal machining operations. The thiophosphates as prepared do have a low pH value when dissolved or dispersed in water, and therefore, it may be desirable to incorporate a corrosion inhibitor, such as sodium nitrite, borax and amines such as morpholine, etc., in addition to the thiophosphate lubricant in the aqueous coolant. Organic or inorganic bases may be used to adjust the acidity to any desired level. When used as lubricants for aqueous coolant solutions, thiophosphates are generally added in amounts ranging from about 0.1 to about weight percent based on the weight of the coolant solution, with about 0.5 to about 3 weight percent the preferred range.

The following examples describe more fully preferred embodiments of this invention.

EXAMPLE I A one liter flask was charged with 100 g. (0.274 equivalent) of anhydrous polyoxyethylene Armeen TD (Aremeen TD is a commercially available higher fatty amine mixture of about 2 wt. percent tetradecyl amine, 24 wt. percent hexadecyl amine, 28 wt. percent octadecyl amine and 46 wt. percent octadecenyl amine) containing 20 moles of ethylene oxide per mole of Armeen TD as shown by the number (20) in parentheses. The charge was heated to 43 C. and 15.2 g. of P S (0.0685 mole) was then added in small portions over a period of about 10 minutes, during which the exothermic heat of reaction was allowed to raise the temperature of the reactants to about 53 C. Heat was then applied and the reactants were stirred at C. for about 5.5 hours. During this reaction period, all of the P 5 was observed to react and the reaction mixture became quite viscous. After the reaction was completed, nitrogen was blown through the resultant product at 115 C. for about 30 minutes to remove trapped hydrogen sulfide. 113.0 g. of a light colored, viscous product was obtained, and analysis indicated that it contained 5.65 wt. percent S and 3.84 wt. percent P.

EXAMPLE II The product of Example I was found to be water soluble, and 1.0 wt. percent of said product was dissolved in water to form an aqueous coolant. This aqueous coolant was treated for its cooling and lubricating properties. A tapping test, whereby pre-drilled holes in steel plates were threaded, was set up as a convenient bench scale test which has shown good precision and correlation with actual field results.

The test apparatus consisted of a drill press, an automatic tapping head, a table to hold the test plate, and means to measure and record torque developed in cutting threads in the holes and the time required for cutting the threads. The aqueous coolant being tested was flowed over the tap and hole in the workpiece and recirculated by means of a small pump.

Each workpiece had 20 holes in it which had to be threaded. The aqueous coolant and also a commercially available, heavy duty, soluble cutting oil were tested. The results are reported in percent efficiency, and since the heavy duty, soluble cutting oil was compared to the aqueous coolant, values of 100 or better indicate superior performance, though aqueous coolants having lesser values are acceptable. The aqueous coolant was also tested for the number of slips occurring during the drilling of the 20 holes.

An aqueous coolant containing 1.0 wt. percent of the product of Example I gave the following results:

Efficiency (percent) No. of Slips Torque Time EXAMPLE III A one liter flask was charged with 130 g. (0.134 equivalent) of polyoxyethylene (20) stearic acid. The charge was heated to 47 C., and 7.5 g. (0.033 mole) of P S was then added in small portions over a period of about 5 minutes during which time the temperature was allowed to rise to 52 C. due to the exothermic heat of reaction. Heat was then applied and the reactants stirred at C. for about 6.5 hours. Nitrogen was blown through the product at 120 C. for 30 minutes to remove trapped hydrogen sulfide. 135.9 g. of thiophosphate product was obtained, and analysis indicated that it contained 1.89 wt. percent S and 1.57 wt. percent P.

EXAMPLE IV A one liter flask was charged with g. (0.126 equivalent) of polyoxyethylene (20) sorbitan triester of tall oil acids. The charge was heated to 27 C., and 7.0 g. (0.0315 mole) of P 8 was added in small portions over a period of about 10 minutes during which the temperature was allowed to rise to 39 C. Heat was then applied and the reactants stirred at 120 C. for about 6 hours. Nitrogen was blown through the product at 120 C. for 30 minutes to remove trapped hydrogen sulfide. 133.0 g.

of product was obtained, and analysis indicated that it contained 1.67 wt. percent S and 1.51 wt. percent P.

6 preparation of these thiophosphate compounds is presented in the following table:

Table I Polyoxyethylene Reactant Amount, Equiv. P 5 P 8 Addition Reaction Reaction Yield,

g. g. Moles Temp., C. Temp, C. Time (hrs) g.

93-93.5% polyoxyethylene (20) Armoen TD-|-3% Ethylene glycol+Il O 130 0. 424 23. 6 0. 106 40-72 120 6 137. 1 Polyoxyethylene tridecyl alcohol 130 0. 171 9. 5 0. 0428 31-42 120 6. 5 133. 7 Polyoxyethylene (10)* Arn'lid HT 130 0. 231 12. 8 0. 0577 43-52 120-125 6. 5 1 10. 8 Polyoxyethylene tertiary hexadccyl Ineroaptan a- 130 0. 157 8. 8 0. 0396 45-48 120 6. 5 135. 5 Iolyoxyetheylne (20) polyoxypropylene (8) butlaminey 130 0. 246 13. 7 0. 0616 10-46 120-125 5. 5 140. 3 Polyoxyethylene (l0) Armeen TD 250 0. 842 46. 7 0.210 31-38 120 G. 75 287. 3 Polyoxyethylene (l5) Armecn TD 250 0. 673 37. 4 0.168 30-36 120 6. 280.0 Polyoxyethylene Arnleen TD. 2. 250 0. 419 23. 3 0. 105 38-43 120 6. 5 267. 0 Polyoxyethylene (15) nonyl phenol 130 0. 169 9. 4 0. 0423 27-33 120 6. 5 136. 2

*Armid HT comprises 25% hexadecane amide, 70% octadecane amide, 5% octadecene amide.

EXAMPLE V EXAMPLE VI The thiophosphate products of Examples III to V were tested as lubricants for aqueous coolants in the manner presented in Example 11. In addition, these products were also tested for solubility in water. The following results were obtained;

Concen- Efiiciency, percent Thiophosphate tratio Solubility No. of Compound Wt. Slips percent Torque Time Example III- 1. 0 Soluble 97 112 2 Example IV 0. 5 100 94 6 Example IV 1. 134 116 1 Example IV 2. 120 123 2 Example IV 3. 133 111 0 Example V 1. 90 86 4 As demonstrated by the above results and the results in example II, the thiophosphate compounds of this invention are good lubricants for aqueous coolants. As shown by these results, the aqueous coolants containing thiophosphate compounds generally performed as well or better with respect to torque and time elficiencies as the heavy duty, soluble cutting oil which is currently used as a coolant for metal machining operations.

EXAMPLE VII Other polyoxyethylene compounds were also reacted with P 8 to prepare thiophosphate compounds. All of these reactions were readily carried out in the manner of Examples I, III, IV and V. The data pertinent to the The term consisting essentially of includes compositions containing the named ingredients in the proportions stated, and any other ingredients which do not deleteriously affect the compositions for the purposes stated in the specification.

Having completely described this invention, what is claimed is:

1. A water-soluble thiophosphate compound prepared by reacting a phosphorus sulfide with a polyoxyethylene derivative of a compound selected from the group consisting of fatty alcohols, fatty amines, fatty amides, fatty acids, partial esters of fatty acids and polyhydric alcohols, partial esters of tall oil acids and polyhydric alcohols and alkyl phenols having from about 8 to about 18 carbon atoms in the alkyl chain, said polyoxyethylene derivative containing a long chain lipophilic radical having from about 12 to about 24 carbon atoms and about 8 to about 35 moles of ethylene oxide per mole of polyoxyethylene compound and having at least one but not more than two hydroxylic functional sites reactive to said phosphorus sulfide, said reactants being present in amounts sufficient to react from about 1.8 to about 3.0 equivalents of hydroxyl in said poly-oxyethylene derivative per phosphorus atom in said phosphorus sulfide.

2. The compound of claim 1 in which the phosphorus sulfide is reacted with a polyoxyethylene derivative of a higher fatty amine mixture.

3. The compound of claim 1 in which the phosphorus sulfide is reacted with a polyoxyethylene derivative of sorbitan triester of tall oil acids.

References Cited by the Examiner UNITED STATES PATENTS 2,631,130 3/53 Bartlett et al 260-125 2,636,862 4/ 53 Watson 252-78 2,647,874 8/53 Da Fano 252-78 2,703,318 3/55 Waddey et a1 26097.5 2,733,235 1/56 Cross et al 260-125 2,830,023 4/58 Hoare 260-125 2,870,132 1/59 Hall et a1 260-97.5 3,001,980 9/61 Tirtiaux et a1 260-125 CHARLES B. PARKER, Primary Examiner.

JULIUS GREENWALD, DANIEL D. HORWITZ,

Examiners. 

1. A WATER-SOLUBLE THIOPHOSPHATE COMPOOUND PREPARED BY REACTING A PHOSPHORUS SULFIDE WITH A POLYOXYETHYLENE DERIVATIVE OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF FATTY ALCOHOLS, FATTY AMINES, FATTY AMIDES, FATTY ACIDS, PARTIAL ESTERS OF FATTY ACIDS AND POLYHYDRIC ALCOHOLS, PARTIAL ESTERS OF TALL OIL ACIDS AND POLYHYDRIC ALCOHOLS AND ALKYL PHENOLS HAVING FROM ABOUT 8 TO ABOUT 18 CARBON ATOMS IN THE ALKYL CHAIN, SAID POLYOXYETHYLENE DERIVATIVE CONTAINING A LONG CHAIN LIPOPHLIC RADICAL HAVING FROM ABOUT 12 TO ABOUT 24 CARON ATOMS AND ABOUT 8 TO ABOUT 35 MOLES OF ETHYLENE OXIDE PER MOLE OF POLYOXYETHYLENE COMPOUND AND HAVING AT LEAST ONE BUT NOT MORE THAN TWO HYDROXYLIC FUNCTIONAL SITES REACTIVE TO SAID PHOSPHORUS SULFIDE, SAID REACTANTS BEING PRESENT IN AMOUNTS SUFFICIENT TO REACT FROM ABOUT 1.8 TO ABOUT 3.0 EQUIVALENTS OF HYDROXYL IN SAID POLYOXYETHYLENE DERIVATIVE PER PHOSPHORUS ATOM IN SAID PHOSPHORUS SULFIDE. 